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USB on MK22FN512xxx12 vs MK22FN1M0Axxx12

Question asked by Corey Wolff on Sep 1, 2017
Latest reply on Sep 5, 2017 by Corey Wolff

I'm trying to prove out USB functionality on my custom PCB with a MK22FN1M0Axxx12 microprocessor.  Since I cannot seem to get USB to enumerate on my hardware, I took a step back and started using the FRDM-K22 boards.


I have two FRDM-K22 boards.  One is completely stock out of the box.  The other has the MK22FN512xxx12 micro swapped out with a MK22FN1M0Axxx12.  I used the FRDM-K22 (K22FN1M) as a proof of concept for another design and we had no problems with SPI, UART and other basic functionalities... so I'm ruling out solder bridges and misaligned pins and whatnot.


Both boards work just fine with the exception of USB0.  The FRDM-K22 (MK22FN512) will work with all the USB example projects, but the MK22FN1M0A will not.  The FRDM board with the MK22FN1M0A micro will always show up as "USB Device Not Recognized".  I realize that the MK22FN1M0A has an MPU whereas the other micro does not, so I think maybe I missed something in that configuration... but I just cannot figure out what.


The micro on the TWR-K21 boards are supposed to be functionally the same as the MK22FN1M0A micro I'm using.  Again, I can get the TWR projects to work on the MK22FN512 but not the MK22FN1M0A.


Does anyone have anything specific I should look at?  Since I have everything working on one board, I cannot imagine it would be that big of a (SW) change to work on the other.  Is there something that needs to be done differently in hardware between the two micros?


I'm currently using the usb_device_cdc_vcom (freertos) example from for the TWR-K21F20M which is stated to be compatible with the MK22FN1M0Axxx12... So I would expect it to work out of the box with just a couple pin muxing changes.